Turbine-blade fastening



March 19, 1929. J. L. RAY 1,705,585

TURBINE BLADE FASTENING Filed Sept. 8, 1924. 2 Sh ets-Sheet 1 WITNES ES:

ATTORNEY INVENTOR I 1' Max ch19, 1929. J. L. m 13705585 TURBINE BLADE FASTENING Filed Sept. 81 1924 2 Sheets-Sheet 2 J. Rag

wnusszs; INVENTOR ATTORNEY Patented Mar. 19, 1929.

(UNITED STATES messes r -rsarorrlce.

JAMES L. RAY, or nssmerou, PENNSYLVANIA, Assienon so wnsrmeriousnfnnnc- TRIC & MANUFACTURING COMPANY, A oo roRArrou or PENNSYLVANIA.

TURBINE-BLADE FASTENING. A

Application filed sieptember 8, 1924.. Serial No. 736,653. 7

My invention relates to turbines, more particularly. to the blade-holding means thereof, and has for its object the provision of apparatus of the character designated which shall be simple of construction and which shall securely hold the blades in place. I

More specifically the object of my invention is to provide means, in a turbine having a blade-holding elemenuwith undercut grooves, for securely fastening the last blade to be inserted in said groove.

Apparatus embodying features of my :in- 'vention is illustrated in the accompanying drawings, in which: Fig. 1'is a fragmentary plan View of a turbine rotor having blades secured therein in accordance with my invention; Fig. 2 is a fragmentary sectional view of the rotor showing a form of under,-

cutgrooves; 3 is a sectional view along,

the line III-III ofFig. 1; Fig. 4 is a sec' tionalview along the line I'V IV of Fig. 1; Fig. 5 is a view similar to Fig. 4 showinga modified form of locking piece; Figs. 6 and? are perspective views of the locking pieces shown in Figs. 3 and 5; and Fig. 8 is a View similar to Fig. 1, but illustrating a method of assembling the blades and locking pieces in the blade-holding element. I

In the construction of elastic-fluid turbines. wherein the blades are secured in an annular undercut groove in the rotor, it is necessary to provide the groove with an enlarged portion. of. sufficient length to permitthe insertion of one or more blades in order that the blades may be inserted in. the groove. The blades are then inserted through the enlarged portion of the groove, moved around the rotor and wedged in place. In completing therow of blades, difficulties have been encountered v in adequately securing the blade or blades in position which of anecessity are located in the enlarged portion of the groove.

In accordance with my invention I provide the enlarged portion of the groove with notches along the sides and provide locking pieces for the blades having. complementary projections fitting the notched portion of the.

groove. -The locking pieces are narrower than the blade root pitch, whereby they may be inserted in the enlarged portion of the groove and still permit theinsertion 'of a blade between them. The groove maybe provided with a single notch along its. side or preferably be provided with a plurality of :notches or serrations in order to secure firm engagement betweenv the locking piece, the side of the 'groovejand the blades. In assembling, the locking pieces are drivenbetween the blade root and thesideof the groove and wedge members'are driven between the locking pieces, thereby providing a sturdy and unitary structure. I prefer to machine the notches so that they extend in a directionznon malto a radius of the blade-holding element intersecting therewith so that when the 10019 ing pieces are driven between the blade root and the side of the blade, they exert a radial force on the bladeroot inwardly of the bladeholding element. 1 l

7 Referring now to the drawings for a fuller understanding of my invention I show-in Figs. 1 to 4:,- inclusive,.a blade-holding 'element such as arotor at 10, said bladeholding element being provided with an undercut groove 11 for holding arow of blades 12. The undercut groove maybe of the form-shown in Fig. 2 or of any other form known to the art whereby the blade-holding element and blade are provided with cooperating surfaces for holding the blades in position and resisting stresses due to centrifugal force, The blades 12 have root portions 13 conforming to the contour of the groove, or may have other forms, not shown, known to those skilled in the art. In order to insert the blades. 12" in the groove 11 it is necessary toprovide. a widened portionof thegroove. To this end, I show at-let a widened portion of the groove 11 for inserting the bladestherein. The widened portion 1 1 is of sufficient length inthis instance to accommodate five blades, though it will be apparent that it might be of any; length so long as one or more blades might be inserted therein. N

The widened portion 14 of the groove 11 has its sides provided with notches 16-16. The notches 16 may be in theform of serrations as shown in Figs. 3 and 4-,'although there may be a single notch on'each side of the groove as shown in Fig. 5. In order to secure the blades injposition in the groove 11, look ing pieces 18, 19,21 and 22 are provided, having one side withprojections 20 corresponding to the notches in the side of the enlarged portion 1450f the groove 11 and having the otherside with a contour conforming to the contour of the blade root.- Upon assembly, these locking pieces are driven fromthe outer portion 14, as shown, between the blade root and the side of the enlarged portion of the groove so as to hold the blades 12 in place in the groove.

' In cutting the notches le I prefer to employ a milling cutter in order to secure a more accurate workmanship. Incutting the notches 16 in this manner, thcrenlarged portionltwill be finished with circular ends as shown in Figs. 1 and 8 In assembling,- after the blade row has been completed except for those blades which are to be located in the enlarged portion 14, I first insert filling pi'eces23'at the ends of the enlarged portion 14, said filling pieceshaving a quarter round contour in section so as to -fit'the circular ends of the enlarged portion 14. I next f insert the locking pieces 18, 19, 21, and 22, similar ones on each side, moving the locking pieces 18 and 19 as far to the left as possible and the locking'piec'es 21 and 22 as far to the right as possible.

The lockingpieces 18, 19, 21 and 22 are made narrower thanthe blade root pitch'as may be'seen from the assembly view in Fig. 8.

By making them in this manner-Land, upon assembly, insertlng them in the manner just described, there is left between 'the lockmg I pieces 19 and 21 just enough space P (Fig. 8)

for the insertion of one blade. This construction permits the'employment of an undercut groove 11 (Fig. 2) in therotor, which has been found very desirable for retaining turbine blades in high velocity rotors.

I next insert the blades through the space Pbetween the locking pieces 19 and 21, moving them to the right and left to their proper positions, finally inserting the last blade com-' pleting the row. The locking piece 19 is next moved to the right and the lockingpiece 21 ito the left followed'by' the lockingpiece 18' being moved'to' the right andthe'locking piece 22 beingimoved to the left to the positions shown' inFig.'1. It will be seen by 're-- ferring to Fig. 3 that'by moving the locking pieces in the manner .just described the cooperating projections and notchesfof the lock- 7 ing pieces and the side of the groove engage i the locking piece and the blade root in order to exerta lateral force against the side of the blade andmorefirmly holding'it in en'- gagement with the blade-holding element.

While the notches 16 may-extend parallel 1 v to the bottom of the groove 11, I prefer to so machine themthat they extend in blade root inwardly of the blade-holding elestraight line'so that upon assembly as prea lateral displacement of the locking pieces, whereby they exert a 'radialforce upon the ment. To this end I show the serrations 16 -viously described there is a'radial as well as in Fig. 3 as extending in a direction normal i to, and bisected by, a radial line 17 intersecting'therewith 'NVith the notches 16 cut in this manner and the locking pieces 18, 19, 21 and 22 in the positions shown in'Fig, 8,when the locking pieces are moved to the right and left in the groove as dc'scribed,there isa radial displacement of the locking pieces inwardly of the blade-holding element, forcing the blades downwardly into the 'bottom'of V the groove 11.

From the foregoing, that I have invented an'improved means for securing blades in the grooveof-azturbine it will be apparent 7 blade-holding element wherein the groove is wider than the root of the blade to be secured.

' .While I have-shown my invention in but two "forms, it will be obvious to those skilled in the'art that itisnot so limited, but is "sus ceptible of various other changesfand modi fications, without departing from the spirit thereof, and "I desire,- therefore, that only i of blades therein, the combination of a turbine blade inserted in the widened porti0n,"a locking piece narrower than the turbine blade root longitudinally of the undercut groove and fittingtheside of the blade root and the groove, and means for lwed-ging thelo'cking,

piece 1n engagement withthe blade root and V the groove. I 2. In a turbine having a rotorfs aid rotor being providedwith an'undercut groove for holding a'row of bladeshaving roots fitting the sides of'the undercut groove, said groove having a widened portion with notched sides for the insertion of blades within the I undercutgroove, a plurality of blades within'the widened portion of the groove, a plurality of locking pieces for holding the blades within the widened portion. said lockingpiecesbeing narrower than the blade root longitudinally. of the undercut groove and fitting the side of the blade root and the side of the groove, and'= means for Wedging the locking pieces in enagement with the blade'root and thewidened' portion of the groove. j v 3. In a turbine, the combination of a bladek holding element having --a' groove with notched sides, said. notches extending transversely of the .axis of rotation. in a direction substantiallyfnormal to. a radius of the bladeholding element intersecting therewith, a blade within the groove, and locking pieces for holding the blade in position, said lockfitting the notches of the groov 4. In a turbine, the combination of a bladeholding element having an undercl'itgroove with a row of blades mounted t-l1Gl.'-ll1,-Sfill ing pieces having complementary projections groove having for arelatively short distance for holding the blades, said groove being widened for a relatively short distance for inserting the blades in the undercut groove, said widened portion having notchedsides, a pluralit-y of blades within the widened portion,

locking pieces for holding the blades in place within the widened portion, said locking pieces being in spaced relation to each other and having projections fitting the notches of the groove. 7 v

6. In a turbine, the combination of a bladeholding element having a groove with serrated sides, said serrations extending transversely of the axis of rotation and in a direction substantially normal to a radius of the blade-holding element intersecting therewith, a blade within the groove, and a locking piece having complementary serrations fitting the serrations of the groove, said locking piece adapted to be driven along the groove at the side of the blade in a direction for exerting a radial force on the blade root inwardly ot' the blade-holding element.

7. In a turbine, the combination ofabladeholding element'having an undercut groove for holding the blades, said groove being widened for a relatively short distancefor inserting the blades in the undercut groove, the widened portion of said groove having serrated sides. said serrations extending transversely of the axis of rotation in a direction substantially normal to a radius of the bladeholding element intersecting therewith, a blade within the widened portion, and looking pieces for holding the blade in the widened portion, said locking pieces having complementary serrations fitting the serrations of the groove, and adapted to be driven between the side of the groove and the blade for exerting a radial force on the blade root inwardly oi the blade-holding element.

8. In a turbine, the combination of a bladeholding element having an undercut groove the serrations of the widened out port-ion and for holding the"blades,*-said groove being widened for a relatively short distance for inserting the blades in the undercut groove,- the widened POItlOH-QJf said groove having serrated side's, said serrations extending transversely-of the axis of: rotation in a direction substantially normal to 'a' radius of the blade holding element intersecting therewith,a'plurality of blades within the widened portion, andlocking pieces for holding the blades in thewidened portion, said locking pieces having one side conforming in con-- tour to the blade root and the other side thereof having complementary serrations fitting adapted to be driven between the blade and the side of the groove in a direction for exerting a radial force inwardly of the blade-holding element.

9. In a turbine,the combination of a bladeholding element having an undercut groove for holding the blades, said groove being widened for a relatively short distance for I insertingthe blades in thenndercut groove,

vthe widened portionof said grooves having serrated sides, said serrations extending transversely of the axes of rotation in a direction substantially normal to a radius of the blade-holding element intersecting therewith, a plurality of blades within the'widened portion, and locking pieces for holding the blades in the widened portion,said locking pieces being in spaced relation to each other" and having one side with serrations fitting the serrations of the widened portion and adapted to be driven between the blade root and theside of the groove in a direction for exerting a radial force inwardly of the bladeholding element, and wedges between adjacent locking pieces. v i

10. In a turbine, the combination of a blade-holding, element having an undercut groove for holding the blades, said groove being widened for a relatively short distance for inserting the blades in the undercut groove, the widened portion of said groove havlng serrated sides, said serrations extend-v ing transversely of the axis of rotation in a direction substantially normal to a radius oi f the blade-holdingelement intersecting therewith, a plurality of blades within the widened portion, and locking pieces for holding the blades in the widened portion, said locking pieces being in spaced relation to each other and having one side with serrations fitting theserrations of the widened portion and adapted to be driven between the blade root and the side of the groove in a direction for exertinga radial force'inwardly of the bladeholding element, and wedges between adj acent locking pieces, and supplementary wedges between the locking pieces on one side of the groove and the blades.

11. In a turbine, the combination of a rotor provided with a circumferential]y extending insertion of blades therein, a row of blades inserted in the groove, a plurality of locking pieces in said widened portion ofthe groove and shdable circumferentially therein, each locking piece having interlocking engage-. '1nentw1ththe side of the widened portion of v the groovefand, the adjacent side of the blade 10 row, the total circumferential Width 01. said locking pieces being less than the circumferential extent ofthe widened portion by ,an

amount as great as the width of one blade.

In testimony whereof I have hereunto subscribed my name this 26th day of August,

1924. c t t t JAMES. L.;RAY; 

